Microchannel plate with respective face electrodes thereof formed to terminate on one face

ABSTRACT

Electron multiplier apparatus comprising a plurality of substantially equal length electron multiplier tubes stacked in a parallel relationship so as to form a cylindrical body known as a microchannel plate. The body has a pair of faces at the ends of the tube and a coating of electrically conducting material is applied to one of the faces and wrapped around the body so as to extend onto the other face. A second conductive coating on said other face has an annular space between it and the first conductive coating and lead wires, adapted to be connected to a voltage source, are connected to the coatings on opposite sides of the space for applying an electric potential between the ends of the multiplier tubes.

United States Patent 151 3,662,207 Thomas et al. 1 May 9, 1972 [54] MICROCHANNEL PLATE WITH 3,341,730 9/1967 Goodrich et al ..313/103 E P T FACE ELECTRODES 3,440,470 4/1969 Decker ..313/103 THEREOF FORMED TO TERMINATE ON ONE FACE Primary Examiner-John S. Heyman Attorney-William F. Thornton, James E. Stephenson and Flame, Hartz, Smith & Thompson 57] ABSTRACT Electron multiplier apparatus comprising a plurality of substantially equal length electron multiplier tubes stacked in a parallel relationship so as to form a cylindrical body known as a microchannel plate. The body has a pair of faces at the ends of the tube and a coating of electrically conducting material is applied to one of the faces and wrapped around the body so as to extend onto the other face. A second conductive coating on said other face has an annular space between it and the first conductive coating and lead wires, adapted to be connected to a voltage source, are connected to the coatings on opposite sides of the space for applying an electric potential between the ends of the multiplier tubes.

6 Claims, 3 Drawing Figures MICROCHANNEL PLATE WITH RESPECTIVE FACE ELECTRODES THEREOF FORMED T TERMINATE ON ONE FACE BACKGROUND OF THE INVENTION Electron multiplier tubes of the type that are stacked so as to form the microchannel plat of this invention are disclosed in U.S. Pat. No. 3,128,408, assigned to the assignee of this application. U.S. Pat. No. 3,341,730, also assigned to the assignee of this application, discloses the stacking of a plurality of multiplier tubes. When the tubes are stacked so as to form the microchannel plate, a conductive coating must be applied to the tube ends which form the faces of the microchannel plate so that a voltage differential can be created across the lengths of the tubes. Past practice required the location of a lead wire adjacent each face of the microchannel plate in order to conduct current to the coatings. This created practical problems because space limitations often preclude the disposition of a lead wire at the coating provided at the input ends of the electron multiplier tubes. The principal object of the present invention, therefore, is to provide a microchannel plate construction enabling the disposition of both lead wires at one face of the microchannel plate.

SUMMARY OF THE INVENTION The microchannel plate of this invention consists of a plurality of small diameter electron multiplier tubes of substantially equal length stacked in a parallel relationship so as to form a cylindrical or wafer-like body having opposite faces at the ends of the tubes. A first conductive coating covers one of the faces and is wrapped around the body so as to extend onto the opposite face. A second conductive coating is applied to the other face so that there is an annular spaced between the coatings on the face which carries both coatings. This arrangement of the coatings enables the disposition of the two lead wires for the coatings on the same side of the microchannel plate. ln a preferred embodiment of the invention an annular disk member of electrically non-conductive material is arranged in a supporting relation with the lead wires and is positioned against the face which carries both coatings so as to electrically engage the lead wires with the coatings on opposite sides of the annular space. This arrangement precludes the necessity for connecting a lead wire to one face of the microchannel plate thereby avoiding the space problems associated with this connection in the past. This invention thus provides an improved microchannel plate construction.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIG. 1 is a sectional view of the microchannel plate of this invention shown in an image intensifier assembly which includes a photocathode and a phosphor screen; and

FIGS. 2 and 3 are transverse sectional views of the microchannel plate of this invention as seen from the lines 2 2 and 33 in FIG. 1.

With reference to the drawing, the microchannel plate of this invention, indicated generally at 10, is shown in FIG. 1 as consisting of a large number of electron multiplier tubes 12, only two of which are shown for convenience of illustration, each of which is provided on its internal surface with a conductive coating 14 of a secondary electron emissive material having a relatively high resistance. The diameter of each tube 12 is relatively small compared to its length and is shown in FIG. 1 of an enlarged diameter relative to its actual size only for convenience of illustration. The tubes 12 are of substantially equal length and are stacked in a parallel relationship so as to form a body 16 of generally cylindrical shape so that the body 16 resembles a wafer or disk in appearance. The body 16 has what will hereinafter be referred to as a first face 18 disposed at one of the ends of the tubes 12 and a second face 20 located at the opposite ends of the tubes 12.

A first electrically conductive coating 22 consisting of a metal such as gold or silver is placed on the entire face 18 such as by vapor deposition or by painting and the coating 22 is extended around the body 16 so that an annular portion 24 thereof extends onto the face 20. A second electrically conductive coating 26, of the same material as the coating 22, is applied to the face 20 so that there is an annular space 28 between the coating 26 and the portion 24 of the coating 22. Both the coatings 22 and 26 are continuous and uninterrupted.

The above described wrap-around configuration of the coating 22 enables the disposition of the necessary lead wires 30 and 32 adjacent only the face 20 thereby obviating the necessity for locating one of the lead wires 30 or 32 adjacent the face 18. In a preferred embodiment of the invention, the lead wires 30 and 32 are supported in an annular disk 34, formed of an insulating material such as glass, which is positioned against the coated face 20 so that the lead wire 30 is electrically engaged with the coating portion 24 and the lead wire 32 is electrically engaged with the coating 26.

The wires 30 and 32 are, during use of the microchannel plate 10, connected to a voltage source so as to cause a flow of current between the coating 22 and the coating 26. This places the desired voltage differential across the tubes 12 which extend between the coatings 22 and 26. A voltage differential across each tube accelerates electrons coming into the tube and also supplies current in the resistive coating 14 to cause the release of secondary electrons when electrons strike any part of the coating 14, as explained in detail in the aforementioned U.S. Pat. No. 3,128,408. All of the tubes 12 then cooperate to form an electron multiplier which can be used in an image intensifier.

The microchannel plate 10 is illustrated in FIG. 1 in an image intensifier assembly which includes a photocathode 36 that emits a small number of electrons for flow through the tubes 12 which greatly multiply the electrons and emit an increased number thereof which are received ona phosphor screen 38. The photocathode 36 must be placed in close proximity to the coating 22, thus making it extremely difficult to satisfactorily assemble a lead wire, such as the lead wire 30, with the coating 22 at a position between the coating 22 and the photocathode 36. The microchannel plate 10 of this invention eliminates the necessity for so locating the lead wire 30 by enabling the location of the lead wire 30 adjacent the lead wire 32 where more space is available.

From the above description it is seen that this invention provides an improved microchannel plate 10 by virtue of the wrap-around construction of the electrically conductive coating 22 thus enabling the disposition of the lead wires 30 and 32 on one side of the microchannel plate 10.

We claim:

1. A microchannel plate comprising a plurality of substantially equal length multiplier tubes stacked in parallel relationship so as to form a body having a first face at one of the ends of said tubes and a second face at the opposite side of said tubes, and means for producing an electric current flow between the ends of said tubes, said means including a first conductive coating substantially entirely covering said first face and wrapped around said body so as to extend onto said second face and a second conductive coating on said second face disposed in a spaced relation with said first conductive coating.

2. A microchannel plate according to claim 1 further including a pair of lead wires disposed adjacent said second face, one of said lead wires being electrically connected to said first conductive coating and the other one of said lead wires being connected to said second conductive coating.

3. A microchannel plate according to claim 1 wherein both said first and second coatings are continuous and uninterrupted.

4. A microchannel plate according to claim 1 wherein said body is substantially cylindrical in shape, said coatings are continuous and uninterrupted and an annular space is provided between said coatings on said second face.

5. A microchannel plate according to claim 4 further including a pair of lead wires connected to said coatings at said second face on opposite sides of said annular space.

6. A microchannel plate according to claim 5 further including a member formed of electrically non-conducting 5 material and arranged in a supporting relation with said lead wires, said member being engaged with said second face so as to electrically connect said lead wires to said coatings.

* i 1 II 1 

1. A microchannel plate comprising a plurality of substantially equal length multiplier tubes stacked in parallel relationship so as to form a body having a first face at one of the ends of said tubes and a second face at the opposite side of said tubes, and means for producing an electric current flow between the ends of said tubes, said means including a first conductive coating substantially entirely covering said first face and wrapped around said body so as to extend onto said second face and a second conductive coating on said second face disposed in a spaced relation with said first conductive coating.
 2. A microchannel plate according to claim 1 further including a pair of lead wires disposed adjacent said second face, one of said lead wires being electrically connected to said first conductive coating and the other one of said lead wires being connected to said second conductive coating.
 3. A microchannel plate according to claim 1 wherein both said first and second coatings are continuous and uninterrupted.
 4. A microchannel plate according to claim 1 wherein said body is substantially cylindrical in shape, said coatings are continuous and uninterrupted and an annular space is provided between said coatings on said second face.
 5. A microchannel plate according to claim 4 further including a pair of lead wires connected to said coatings at said second face on opposite sides of said annular space.
 6. A microchannel plate according to claim 5 further including a member formed of electrically non-conducting material and arranged in a supporting relation with said lead wires, said member being engaged with said second face so as to electrically connect said lead wires to said coatings. 